2型糖尿病中国地鼠模型构建与小檗碱对肝脏过氧化物酶体增殖体激活受体及其靶基因表达的影响

背景：研究表明小檗碱可用于治疗2型糖尿病,但小檗碱治疗糖尿病胰岛素抵抗尤其是肝脏脂诱性胰岛素抵抗的分子机制仍不明确。 目的：观察小檗碱对2型糖尿病中国地鼠模型肝脏过氧化物酶体增殖体激活受体及其靶基因表达的影响。 方法：以高脂饮食及结合小剂量链脲菌素的方法建立胰岛素抵抗和2型糖尿病中国地鼠模型。建模后随机分成4组：对照组给予普通饮食,胰岛素抵抗组给予高脂饮食,2型糖尿病组给予高脂饮食+小剂量链脲菌素,2型糖尿病小檗碱治疗组给予高脂饮食+小剂量链脲菌素+小檗碱,治疗9周。 结果与结论：实时定量PCR结果显示与对照组相比,胰岛素抵抗及2型糖尿病组地鼠肝脏过氧化物酶体增殖体激活受体α,β/d,酰基辅酶A氧化酶,肉碱棕榈酰转移酶1和中链酰基辅酶A脱氢酶的表达降低(P < 0.05),而固醇调节元件结合蛋白1c,2,过氧化物酶体增殖体激活受体γ,脂蛋白脂酶,脂肪酸转运者(FAT/CD36)和脂肪酸结合蛋白(ap2)的表达增加(P < 0.05)。结果证实,小檗碱可改善胰岛素抵抗,并逆转了氧化物酶体增殖体激活的受体及其靶基因表达的改变,小檗碱治疗2型糖尿病地鼠脂诱性胰岛素抵抗的分子机制与氧化物酶体增殖体激活的受体及其靶基因表达的改变相关。     

针刺2型糖尿病大鼠脂肪细胞因子的变化*☆

背景：脂肪细胞因子在2型糖尿病发病中的作用尚未明确;针灸治疗2型糖尿病早中期具有良好的疗效,那么针刺对脂肪细胞因子是否也有影响呢？ 目的：验证脂肪细胞因子与2型糖尿病的关系以及针刺对2型糖尿病机体脂肪细胞因子的影响。 设计、时间及地点：随机对照动物实验,于2006-08/2007-01在南京中医药大学动物实验中心完成。 材料：刚断乳的SD雄性大鼠100只,平均体质量50 g左右,随机分为普通饲料组20只,高脂饲料组80只,高脂饲料组大鼠体质量高于普通饲料组平均体质量20%为食源性肥胖大鼠。 方法：给40只食源性肥胖大鼠腹腔注射小剂量链脲霉素,成功造成2型糖尿病模型27只,随机分为模型组、针刺组(针刺后三里、内庭和胰俞,1次/d)及优降糖组[格列本脲片1.6 mg/kg给药,1次/d],每组各9只,处理4周,与随机抽取的9只正常饲料大鼠做对照。 主要观察指标：以快速血糖仪检测空腹血糖、放免法检测空腹胰岛素、ELISA法检测血清脂联素、抵抗素和肿瘤坏死因子α质量浓度。 结果：模型组空腹血糖、空腹胰岛素、肿瘤坏死因子α明显高于正常组(P < 0.05或0.01);针刺组与模型组比较,空腹血糖、空腹胰岛素、肿瘤坏死因子α明显下降(P < 0.05或0.01),接近正常组水平;优降糖组与模型组比较,空腹血糖明显下降(P < 0.01),接近正常组水平,空腹胰岛素和肿瘤坏死因子α有所下降,和正常组仍有差异;模型组、正常组、针刺组、优降糖组血清脂联素和抵抗素水平差异无显著性意义(P > 0.05)。 结论：血清脂联素和抵抗素水平与2型糖尿病的发病无明显关系,血清肿瘤坏死因子α可能参与了2型糖尿病的发病机制;针刺和优降糖均具有明显的降血糖、改善胰岛素抵抗、抑制血清肿瘤坏死因子α作用,针刺作用优于优降糖。     

实验性2型糖尿病大鼠模型及其周围神经病变特点

目的:制备发病过程类似人类2型糖尿病的大鼠模型,并观察其周围神经病变特点。方法:用高糖高脂饲料喂养Wistar大鼠诱发胰岛素抵抗,然后用亚致病剂量的链脲菌素(STZ)腹腔注射,诱发高血糖。在不同的时间观察其肌电图和周围神经的病理改变。结果:此方法制备的2型糖尿病大鼠周围神经病变特点有:1、坐骨神经运动传导速度降低。动作电位的波幅降低;2、腓肠神经有髓神经纤维的数目、有髓神经纤维的总截面积和纤维密度较正常对照组减少。结论:Wistar大鼠用高糖高脂饮食结合小剂量STZ注射可成功制备2型糖尿病大鼠模型,并具有典型的周围神经病变特点,是研究2型糖尿病及其慢性并发症的理想模型。     

糖尿病大鼠海马内PAI-1的变化及米诺环素对其的影响

目的 探讨纤溶酶原激活物抑制剂-1(PAI-1)在2型糖尿病大鼠海马中的表达情况以及米诺环素对PAl.1表达的影响.方法 高糖高脂饮食加小剂量链脲佐菌素造2型糖尿病模型,将SD大鼠随机分为正常组、糖尿病模型组、米诺环素治疗组,造模成功1周后,米诺环素组每天腹腔注射米诺环素45mg/kg,糖尿病模型组和正常组腹腔注射等量的牛理盐水,连续给药2周,然后取大鼠海马组织,免疫组化检测各组大鼠海马中PAI-1的表达.结果 免疫组化结果分析示正常组、糖尿病组、米诺环素组阳性神经元的平均光密度值(MOD值)分别为0.109±0.007、0.195±0.009、0.161±0.012,与正常组比较,糖尿病组和米诺环素组PAI-1表达的差异均有统计学意义(P＜0.01),糖尿病组和米诺环素组比较差异也有统计学意义(P＜0.01).结论 2型糖尿病大鼠海马神经元内PAI-1的表达异常增高,米诺环素可减少大鼠海马神经元内PAI-1的表达,这可能是米诺环素保护糖尿病认知功能障碍的机制之一.     

艾塞那肽对糖尿病周围神经损伤大鼠的神经保护作用

目的 探讨艾塞那肽(EX)对糖尿病周围神经损害大鼠的神经保护作用.方法 将34只健康雄性Wistar大鼠随机分为正常对照(NC)组、糖尿病组、EX小剂量治疗(EXmin)组及大剂量治疗(EXmax)组.后3组大鼠给予脂肪乳灌胃,14 d后进行口服葡萄糖耐量试验并测算胰岛素抵抗指数;通过腹腔注射链脲佐菌素建立糖尿病模型....     

HU-MSCS诱导为胰岛样细胞移植治疗糖尿病大鼠的研究

摘要目的: 观察人脐带间充质干细胞体外诱导分化为胰岛β样细胞及治疗糖尿病大鼠的效果方法：经培养，当细胞融合至70%~80%，诱导人脐带间充质干细胞向胰岛样细胞团分化，并用双硫腙染色法进行鉴定。采用完全随机法将40只SD大鼠分为正常对照组6只，链脲佐菌素组34只。空腹12h后，链脲佐菌素组腹腔注射链脲佐菌素（70mg/kg）和柠檬酸钠缓冲液(0.1 mol/L) 。大鼠分别于注射前、后48 h、第5 d和第8 d空腹断尾采血, 测定全血血糖浓度。选用连续2次血糖浓度高于16.7mmol/L的大鼠作为糖尿病模型。采用完全随机法从已成模的糖尿病大鼠中选出30只分为3组：胰岛样细胞移植组12只，进行肾被膜下胰岛样细胞团移植, 每只大鼠注入胰岛样细胞2×106 个；脐带间充质干细胞组12只，肾被膜下注入未进行诱导的脐带间充质干细胞, 细胞数2×106个；糖尿病对照组6 只, 肾被膜下移植不含细胞的培养液。3 组大鼠均于移植前及移植后48 h 测定空腹血糖浓度, 每周定点测空腹血糖及称体重1次。结果:（1）成功将人脐带间充质干细胞体外诱导分化为胰岛样细胞团, 双硫腙染色阳性。（2）胰岛样细胞团移植组大鼠移植2周，血糖浓度显著降低, 且血糖下降的趋势一直维持至第6周。脐带间充质干细胞组移植2周，血糖浓度显著下降，但是4周后血糖浓度出现上升。糖尿病对照组大鼠血糖浓度一直处于糖尿病血糖浓度范围内。结论：人脐带间充质干细胞体外可诱导分化为胰岛样细胞团，并对糖尿病大鼠有治疗作用。     

2型糖尿病伴牙周病大鼠牙槽骨中转化生长因子β1 mRNA的表达*

背景：研究表明糖尿病可以增加牙周病的发病风险,糖尿病可以引起骨代谢的紊乱并导致骨质疏松症,但其具体机制尚未阐明。 目的：通过对大鼠牙槽骨转化生长因子β1 mRNA表达及根尖区骨密度变化的测定,探究2型糖尿病促进牙周病变的机制。 方法：采用高糖高脂饮食喂养、小剂量链脲佐菌素、一次性腹腔注射及正畸结扎丝结扎的方法建立2型糖尿病伴牙周病SD大鼠模型。应用RT-PCR技术检测实验大鼠牙槽骨中转化生长因子β1 mRNA表达,并对大鼠牙槽骨进行骨密度测量及病理切片光镜观察。 结果与结论：与正常对照组、2型糖尿病组、牙周病组比较,2型糖尿病伴牙周病组大鼠牙槽骨中转化生长因子β1 mRNA表达最高,骨密度值最低(P < 0.01)。2型糖尿病伴牙周病组大鼠牙槽骨有骨质疏松倾向。结果提示2型糖尿病可能通过转化生长因子β1的过表达来促进牙槽骨骨质疏松,进而说明2型糖尿病可能通过转化生长因子β1的过表达来促进牙周病变。 关键词：糖尿病;牙周病;牙槽骨;转化生长因子β1;骨密度     

牛磺酸对糖尿病大鼠周围神经病变的保护作用

目的研究牛磺酸对糖尿病大鼠坐骨神经结构、功能以及神经生长因子mRNA表达的影响。方法54只雄性Wistar大鼠随机分为模型组、牛磺酸组和正常对照组,每组各18只。大鼠于禁食12h后,一次性腹腔注射1%链脲佐菌素诱导制备糖尿病大鼠模型;72h后尾静脉采血测定血糖水平,>16.7mmol/L者纳入实验。模型制备后第8周末于光学显微镜和电子显微镜下观察坐骨神经形态改变。同时行逆转录聚合酶链反应半定量分析神经生长因子mRNA含量;化学比色法检测血清丙二醛含量;采用MS302多媒体生物信号系统分别记录模型制备后第4周、8周时大鼠坐骨神经运动神经传导速度。结果(1)与模型组相比,牛磺酸对链脲佐菌素诱导的糖尿病大鼠的体质量和血糖水平无明显改善(P>0.05)。(2)与正常对照组相比,模型组和牛磺酸组大鼠在注射链脲佐菌素后第8周血清丙二醛水平明显升高(均P<0.01),但牛磺酸组低于模型组(P<0.01)。(3)与正常对照组相比,模型组大鼠坐骨神经运动神经传导速度在制模后第4周、8周明显减慢(均P<0.01);同期牛磺酸组与模型组间差异亦有显著性意义(均P<0.05)。(4)病理观察显示,模型组和牛磺酸组大鼠在注射链脲佐菌素后第8周均表现为明显的损伤反应,但牛磺酸组病变程度较轻。(5)与正常对照组相比,注射链脲佐菌素后第8周模型组大鼠神经生长因子mRNA表达水平显著下降(P<0.01),牛磺酸组表达水平高于模型组(P<0.01)。结论牛磺酸对糖尿病周围神经病变的防治作用不是直接通过降低血糖水平,而可能是通过有效清除自由基,减轻脂质过氧化,上调神经生长因子mRNA表达而改善神经损伤实现的。     

脐带源间充质干细胞与大鼠胰腺细胞共培养向胰岛样细胞分化及移植治疗1型糖尿病★

背景：脐带Wharton’s Jelly中间充质干细胞可以向胰岛样细胞诱导分化。 目的：验证脐带源间充质干细胞与大鼠胰腺细胞共培养向胰岛样细胞诱导分化的可能性，并观察移植后对糖尿病大鼠血糖的影响。 方法：分离、诱导、传代脐带Wharton’s Jelly中间充质干细胞，再与大鼠胰腺细胞共培养，诱导成胰岛细胞团样组织。将大鼠分为3组，正常对照组不进行移植及造模；模型组仅制备糖尿病大鼠模型；实验组造模后将胰岛样细胞移植入糖尿病大鼠肾脏包膜。 结果与结论：脐带Wharton’s Jelly细胞培养中有细胞从组织块中爬出，第7天形态发生变化，贴壁细胞部分变成梭形。分离培养的细胞表达具有间充质干细胞表面特有标志CD44、CD29、CD105，不表达CD34、CD45、CD14。诱导第7，10天PDX-1及人胰岛素强染色；胰岛素及C-肽浓度较单纯培养组明显升高；PDX-1及人胰岛素mRNA诱导第7、10天较高表达。移植第1周大鼠尾尖血糖链脲佐菌素实验组明显低于模型组(P < 0.01)，但明显高于正常照组(P < 0.01)。8周链脲佐菌素实验组肾脏被膜下发现胞核染棕色染色的Brdu阳性、胞浆棕色染色的胰岛素阳性细胞。结果表明，脐带Wharton’s Jelly中存在脐带源间充质干细胞，与大鼠胰腺细胞共培养可促进间充质干细胞向胰岛样细胞诱导分化，移植入糖尿病大鼠肾脏被膜下，可显著降低糖尿病大鼠血糖。     

神经肽Y Y5受体基因反义寡核苷酸脑室给药对伴糖尿病缺血再灌注大鼠血清瘦素与TNF-α的影响

目的观察神经肽Y Y5(NPY Y5)受体基因反义寡核苷酸脑室给药对伴糖尿病缺血再灌注大鼠血清瘦素、胰岛素与TNF—α的影响。方法链脲佐菌素空腹腹腔注射制备糖尿病大鼠模型，线栓法闭塞大脑中动脉制作脑缺血再灌注大鼠模型；治疗组经导管向脑室注入50μg(5U／μl)NPY Y5受体基因反义寡核苷酸，每天3次给药，连续应用3天；采用ELISA双抗体夹心法测定血清TNF-α与瘦素含量，放射免疫法测定胰岛素含量。结果缺血再灌注损伤后，大鼠血清瘦素、胰岛素、TNF—α水平较对照组显著升高；NPY Y5受体基因反义脱氧核苷酸侧脑室注射干预后，其血清瘦素、胰岛素水平明显下降，TNF—α水平显著降低。结论神经肽Y Y5受体基因反义寡核苷酸侧脑室给药可降低伴糖尿病缺血再灌注大鼠的血清瘦素、TNF—α与胰岛素水平，改善外周瘦素抵抗与胰岛素抵抗，促进脑梗死恢复。     

Effects of Orchidectomy and Testosterone Replacement on Numbers of Kisspeptin‐, Neurokinin B‐, and Dynorphin A‐Immunoreactive Neurones in the Arcuate Nucleus of the Hypothalamus in Obese and Diabetic Rats

Neurones expressing kisspeptin, neurokinin B and dynorphin A, located in the arcuate nucleus of the hypothalamus (ARC), are important regulators of reproduction. Their functions depend on metabolic and hormonal status. We hypothesised that male rats with high‐fat diet‐induced obesity (DIO) and/or streptozotocin‐induced diabetes mellitus type 1 (DM1) and type 2 (DM2) will have alterations in numbers of immunoreactive (‐IR) cells: kisspeptin‐IR and/or neurokinin B‐IR and dynorphin A‐IR neurones in the ARC in the sham condition. In addition, orchidectomy alone (ORX) and with testosterone treatment (ORX+T) will unmask possible deficits in the response of these neurones in DIO, and/or DM1 and DM2 rats. Rats were assigned to four groups: a control (C) and one diabetic group (DM1) were fed a regular chow diet, whereas the obese group (DIO) and the other diabetic group (DM2) were fed a high‐fat diet. To induce diabetes, streptozotocin was injected. After 6 weeks, each group was divided into three subgroups: ORX, ORX+T and sham. After another 2 weeks, metabolic and hormonal profiles were assessed and immunocytochemistry was performed. We found that: (1) under sham conditions: (i) DM1 and DM2 animals had higher numbers of kisspeptin‐IR cells than controls and (ii) DM2 rats had increased numbers of neurokinin B‐IR and dynorphin A‐IR cells compared to C animals; (2) ORX and ORX+T treatments unmasked deficits of the studied neurones in DM1 and DM2 but not in DIO animals; and (3) DIO, DM1 and DM2 rats had altered metabolic and hormonal profiles, in particular decreased levels of testosterone. We concluded that alterations in numbers of kisspeptin‐IR and neurokinin B‐IR neurones in the ARC and their response to ORX and ORX+T may account for disruptions of metabolic and reproductive functions in diabetic but not in obese rats.     

Retinal changes in an experimental model of early type 2 diabetes in rats characterized by non-fasting hyperglycemia

Diabetic retinopathy is a leading cause of acquired blindness in young, but also in elder adults, mostly affected by type 2 diabetes mellitus (T2DM). The aim of this work was to develop an experimental model of early human T2DM in adult rats, and to analyze retinal functional, morphological, and biochemical changes arising during the early stages of the moderate metabolic derangement. For this purpose, animals were divided in four groups: adult male Wistar rats receiving: tap water and citrate buffer i.p. (group 1), tap water with 30% sucrose and citrate buffer i.p. (group 2), tap water and 25mg/kg i.p streptozotocin (STZ, group 3), or 30% sucrose and STZ (group 4). Fasting and postprandial glycemia, fructosamine and serum insulin levels were assessed. In addition, i.p. glucose and insulin tolerance tests were performed. Retinal function (electroretinogram, ERG) and morphology (optical microscopy), retinal nitric oxide synthase (NOS) activity (using (3)H-arginine), lipid peroxidation (thiobarbituric acid reactive substances, TBARS), and TNFα levels (ELISA) were evaluated. At 6 and 12 weeks of treatment, animals which received a sucrose-enriched diet and STZ showed significant differences in most metabolic tests, as compared with the other groups. At 12 weeks of treatment, a significant decrease in the ERG a- and b- wave and oscillatory potential amplitudes, and a significant increase in retinal NOS activity, TBARS, TNFα, glial fibrillary acidic protein in Müller cells, and vascular endothelial growth factor levels were observed. These results indicate that the combination of diet-induced insulin resistance and a slight secretory impairment resulting from a low-dose STZ treatment mimics some features of human T2DM at its initial stages, and provokes significant retinal alterations.     

Characterization of diet-induced obese rats that develop persistent obesity after 6 months of high-fat followed by 1 month of low-fat diet

A subset of Sprague-Dawley rats developed persistent obesity when maintained on a high-fat diet for 6 months followed by a low-fat diet for 1 month, while another subset from the same cohort of rats remained lean on the same diet regimens. The diet-induced obese (DIO) rats had higher energy intake than expenditure, while diet-resistant (DR) rats maintained energy balance. DIO rats also had an increased respiratory quotient and higher levels of plasma leptin, insulin and cholesterol. In the hypothalamic areas, DIO rats had elevated NPY and AGRP mRNA, but not MCH mRNA. Our data suggest that the increase in hypothalamic expression of NPY and AGRP may contribute to the development of persistent obesity in DIO rats.     

The level of NPY receptor mRNA expression in diet-induced obese and resistant mice

Some mice become obese whereas others remain lean when raised on a high-energy diet. This study examined the levels of neuropeptide Y (NPY), and of Y1, Y2, Y5 and leptin receptor mRNA expression in the hypothalamic arcuate nucleus (Arc) of chronic high-energy diet-induced obese (DIO) and resistant (DR) mice. Forty mice were divided into two groups and fed either a high-fat (HF: 40% of calories from fat, 20% of calories from saturated fat; n=34) or low-fat (LF: 10% of calories from fat, 1% from saturated fat; n=6) diet. After 22 weeks of feeding, visceral fat accumulation was 69% higher in DIO mice compared with DR mice, and the former showed a moderate level of glucose intolerance. In DIO mice, the levels of NPY and leptin receptor mRNA expressions were significantly higher than in LF mice (+32 and +14%, P<0.001 and 0.05 respectively), indicating central leptin resistance, whereas the DR and LF groups did not differ. The level of Y2 receptor mRNA expression was similar between the DIO and LF groups but, importantly, was reduced approximately 20% in DR mice (P<0.005). The level of Y5 receptor mRNA was 36% lower in DR mice than DIO mice (P<0.05). The differences between DIO and DR mice identified by this study may assist in a better understanding of genetic predisposition to an increased fat deposition induced by a chronic high-fat diet. A low level of Y2 and Y5 receptor mRNA expression may contribute to the prevention of chronic high-energy diet-induced obesity in DR mice.     

Reduced brain CRH and GR mRNA expression precedes obesity in juvenile rats bred for diet-induced obesity

To assess the role of endogenous peptides involved in stress responsivity in the development of diet-induced obesity (DIO), selectively bred DIO and diet-resistant (DR) male were weaned onto a low fat (4.5%) chow diet at 3 weeks of age and then fed either chow or a 31% fat by energy content (high energy (HE)) diet for 9 days beginning at 4 weeks of age. Regardless of diet, DIO rats gained more weight than DR rats but did not show the selective DIO weight gain trait characteristic of older DIO rats fed HE diet. At this early age, both DR and DIO rats on HE diet ate more and had higher leptin levels but gained less body weight and had lower feed efficiency (body weight gain (g)/food intake (kcal)) than their chow-fed controls. HE diet also prevented the decline in 24h urine corticosterone levels from the third to fifth week observed in chow-fed rats. Terminally, DIO rats had lower hippocampal glucocorticoid receptor (GR) and amygdalar central nucleus corticotrophin-releasing hormone (CRH) mRNA than DR rats, regardless of their diets. Taken together with prior studies in these rats, there appears to be a critical period between 3 and 5 weeks of age when DIO and DR rats are not phenotypically different and hypothalamo-pituitary-adrenal (HPA) function is rapidly changing. The reduced expression of brain GR and CRH expression at the end of this period might contribute to the propensity of DIO rats to become obese selectively on HE diet after 5 weeks of age.     

High fat diet affects reproductive functions in female diet-induced obese and dietary resistant rats

The incidence of ovulatory disorders is common in obese animal models. The mechanism behind this effect is unclear. We hypothesised that a high-fat (HF) diet induces alterations in neuroendocrine mechanisms resulting in anovulation in diet-induced obese (DIO) animals. Adult female DIO and diet-resistant (DR) rats were fed either chow or a HF diet (45% calories from fat) for 6 weeks. Oestrous cyclicity and body weight were monitored regularly. At the end of treatment, rats were implanted with a jugular catheter to monitor luteinising hormone (LH) levels on the day of pro-oestrous. Rats were sacrificed on the next pro-oestrous, and their brains and ovaries were collected. Plasma from trunk blood was analysed for oestradiol and leptin concentrations. Ovaries were fixed and sectioned for histological analysis. Brains were removed, frozen and sectioned, and norepinephrine (NE) concentrations in discrete hypothalamic areas were measured using high-performance liquid chromatography with electrochemical detection. A HF diet exposure affected oestrous cyclicity in both DIO and DR rats, with the effect being more pronounced in DIO animals. HF diet exposure increased leptin levels in both DIO and DR rats. Oestradiol levels were low in the DIO-HF group. NE levels in the hypothalamus were unaffected by HF diet or genotype. A normal LH surge was observed in DR-Chow rats and LH levels were low in the remaining groups. These results lead to the conclusion that DIO rats have an inherently reduced reproductive capacity and exposure to a HF diet decreases it further. A reduction in oestradiol and LH surge levels could contribute to this effect; however, the underlying mechanisms need to be investigated further.     

Differential expression of 5-HT(2A) and 5-HT(2C) receptor mRNAs in mice prone, or resistant, to chronic high-fat diet-induced obesity

The present study examined the levels of 5-HT(2A) and 5-HT(2C) (2A and 2C receptors of 5-hydroxytryptamine; serotonin) receptor messenger RNA (mRNA) expressions in the brain of chronic high-fat diet-induced obese (DIO) and obese-resistant (DR) mice. Thirty-one mice were used in this study. Twenty-four mice were fed with a high-fat diet (HF: 40% of calories from fat) for 4 weeks and then classified as the DIO (n = 8) or DR (n = 8) mice according to the highest and lowest body weight (BW) gainers. Seven mice were placed on a low-fat diet (LF: 10% of calories from fat) and were used as controls. After 20 weeks of feeding, the visceral fat accumulation was 620 +/- 42 mg in the DIO group versus 198 +/- 89 mg in the DR and 84 +/- 18 mg in the LF groups. Using quantitative in situ hybridization techniques, levels of 2A and 2C serotonin (5-HT) receptor mRNAs were measured in multiple brain sections of mice from the three groups. Most regions did not differ between groups but, importantly, the DIO mice had a significantly higher level of 5-HT(2A) receptor mRNA expression in the olfactory nucleus (Olf) compared to the DR and LF mice (+30% and +37%, respectively). The levels of Olf 5-HT(2A) receptor mRNA expression were related to body fat mass. The level of 5-HT(2C) mRNA receptor expression in the ventromedial hypothalamic (VMH) nucleus was 40% higher in the DIO mice than in the LF mice. Furthermore, the 5-HT(2C) receptor mRNA expression in the posterodorsal part of the medial amygdaloid (MePD) nucleus was 25% higher in the DIO mice than in the DR mice. The level of VMH 5-HT(2C) receptor mRNA expression was correlated with body fat mass. In conclusion, this study has demonstrated differentially regulated levels of the 5-HT(2A) and 5-HT(2C) receptor mRNA expressions in the specific brain regions of the DIO and DR mice. It provides neural anatomical bases that the 5-HT(2C) receptors positively influence satiety center (VMH) while the 5-HT(2A) receptor regulates olfactory sensory effects. The findings also assist us to understand the role of these receptors in mice susceptible or resistant to diet-induced obesity.     

胰岛素抵抗大鼠血糖正常阶段颈动脉内皮细胞结构改变及可能机制

目的:观察胰岛素抵抗(IR)大鼠血糖正常阶段颈动脉内皮细胞超微结构病理改变。方法:普通饲料喂养的SD大鼠为正常对照,高脂饲料喂养SD大鼠6周复制IR模型。透射电镜观察颈动脉内皮超微结构;应用钳夹法评价大鼠的胰岛素敏感性;酶联免疫方法测定甘油三酯(TG)、胆固醇(TC)、高密度脂蛋白胆固醇(HDL)、低密度脂蛋白胆固醇(LDL)、空腹胰岛素(FIN)、游离脂肪酸(FFA)。结果:IR大鼠颈动脉电镜下可见部分内皮细胞和内皮下结构的病理性改变。IR大鼠实验结束时FBG及PBG2h与正常对照组比较无显著差异(P>0.05);与正常对照组相比IR大鼠血浆FINS、TG、TC、FFA水平明显高于正常对照组(P<0.05);胰岛素敏感性指数(ISI)显著降低(P<0.05);两组高密度脂蛋白(HDL)及低密度蛋白(LDL)水平比较差异无显著性(P>0.05)。结论:结论:高脂膳食诱发的IR大鼠在血糖正常阶段已存在颈动脉内皮超微结构的病理性改变,高胰岛素血症和脂代谢紊乱在内皮损害中可能发挥了重要作用。     

Nutritional regulation of hypothalamic leptin receptor gene expression is defective in diet-induced obesity

Leptin action in the hypothalamus plays a critical role in maintaining normal food intake and body weight. Hyperleptinaemia is associated with obesity in humans and animal models, suggesting a state of leptin resistance. Although the mechanism of leptin resistance is not clearly understood, alterations in leptin receptor (Ob-R) gene expression have been proposed as a potential mechanism mediating modifications in leptin action in obesity and during changes in nutritional status (fed/fasted). The current study examined the effects of diet-induced obesity (DIO) made by feeding rats a high fat diet for 9 weeks, and nutritional status on levels of long form (Ob-Rb) and total (Ob-Rtot) Ob-R mRNA expression in the hypothalamus. In the fed state, hypothalamic Ob-Rb mRNA and Ob-Rtot mRNA levels were similar in DIO and control standard chow fed rats (SC) despite hyperleptinaemia in DIO rats. However, although an overnight fast moderately increased hypothalamic Ob-Rb mRNA levels in SC rats, fasting did not increase Ob-Rb mRNA levels in DIO rats. To address the possibility that elevated leptin concentration in DIO rats may mediate an alteration in OB-R mRNA levels, we examined the effects of adenovirus-mediated hyperleptinaemia on Ob-R gene expression in SC rats. Despite substantially elevated plasma and cerebrospinal fluid concentrations of leptin, hypothalamic Ob-R mRNA levels were similar in both groups. In conclusion, the current study demonstrates that DIO is associated with a loss of nutritional regulation of hypothalamic Ob-R mRNA levels, and that hyperleptinaemia is not sufficient to alter Ob-R mRNA expression.     

Effects of diet and obesity on brain α1- and α2-noradrenergic receptors in the rat

The chronic feeding of a sweetened condensed milk/corn oil diet (CM diet) to adult male rats produced significant increases in body weight and levels of plasma insulin in 34% of the rats fed this diet with respect to chow-fed controls. Levels of alpha 1-noradrenergic receptor binding were lower (32%) in the hypothalamic ventromedial nucleus (VMN) of only those rats which became obese (DIO rats) with respect to both chow-fed controls and those rats which resisted the development of obesity on the CM diet (DR rats). Also, alpha 1-noradrenergic binding was inversely proportional to body weight gain in the VMN (r = -0.831). alpha 2-Noradrenergic receptors were 30-37% lower in both the DIO and DR rats in the dorsomedial nucleus and dorsal area of the hypothalamus, and the medial dorsal area and nucleus reuniens of the thalamus. The similar decreases in alpha 2-noradrenergic receptors in both the DIO and DR rats in these areas suggested that dietary factors alone were responsible for these changes. There were no significant differences from chow-fed rats for hypothalamic dopamine (D2) or beta-noradrenergic (beta 1- and beta 2-) receptors in either DR or DIO rats. These results indicate that VMN alpha 1-noradrenergic receptors co-vary with body weight and implicate a role for alpha 1-receptors in the VMN in the central neuronal regulation of body weight.